Mercator projection distort size, especially Greenland and Africa

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Everydata: The Misinformation Hidden in the Little Data You Consume Every Day by John H. Johnson


Affordable Care Act / Obamacare, Black Swan, business intelligence, Carmen Reinhart, cognitive bias, correlation does not imply causation, Daniel Kahneman / Amos Tversky, Donald Trump,, Kenneth Rogoff, labor-force participation, lake wobegon effect, Long Term Capital Management, Mercator projection, Mercator projection distort size, especially Greenland and Africa, meta analysis, meta-analysis, Nate Silver, obamacare, p-value, PageRank, pattern recognition, randomized controlled trial, risk-adjusted returns, Ronald Reagan, statistical model, The Signal and the Noise by Nate Silver, Tim Cook: Apple, wikimedia commons, Yogi Berra

Sailors got their straight lines for navigation at great expense, as Mercator’s map distorted the size of nearly everything on it. Even worse, the distortion wasn’t equal; the farther an object is from the equator, the more distorted it appears. In practical terms, this means that objects closer to the poles appear to be much larger, relatively speaking, than objects closer to the equator. This artifact is commonly known (to cartographers, at least) as “the Greenland problem” because, on a Mercator map, it looks like Greenland is about the same size as Africa. But it’s not. In fact, it’s not even close. If you compare the two based on land area, Africa is approximately 14 times larger than Greenland. But Africa is on the equator (hence, less distortion) while Greenland sits largely above the Arctic Circle, and therefore looks much larger on a Mercator map than it really is.2 So what’s the problem? Well, besides a few generations of confused schoolchildren, our concern is that the size (and perceived size) of an object has real implications in the real world.


pages: 367 words: 99,765

Maphead: Charting the Wide, Weird World of Geography Wonks by Ken Jennings


Asperger Syndrome, augmented reality, Bartolomé de las Casas, Berlin Wall, British Empire, clean water, David Brooks, don't be evil, dumpster diving, Eratosthenes, game design, Google Earth, helicopter parent, hive mind, index card, John Harrison: Longitude, John Snow's cholera map, Mercator projection, Mercator projection distort size, especially Greenland and Africa, Mikhail Gorbachev, New Journalism, openstreetmap, place-making, Ronald Reagan, Saturday Night Live, Skype, Stewart Brand, Tacoma Narrows Bridge, traveling salesman, urban planning

In 1569, the Flemish cartographer Gerardus Mercator drew a world map using a cylindrical projection that would neatly render a rhumb line—a ship’s course in a constant direction, like west or north-northeast—as a straight line.* The problem is that this kind of projection inflates the polar regions way out of proportion—in fact, on such a map, the poles can never even be drawn, because they’re an infinite distance from the Equator.† Mercator maps were still used everywhere when I was growing up—classrooms, nightly newscasts, stamps, government briefing rooms—and so my generation grew up thinking that Greenland was bigger than Africa, since Greenland is oversized fourteenfold on Mercator maps. Of course, all map projections have to fudge somewhere, whether on area or on direction. Imagine trying to flatten an orange peel onto a flat surface, and as it tears and scrunches, you’ll see the problem: something’s got to give.* But the Mercator map stayed so popular in the West for so long, at least in part, because of how helpful its particular distortions were.


pages: 306 words: 79,537

Prisoners of Geography: Ten Maps That Explain Everything About the World by Tim Marshall


9 dash line, Admiral Zheng, anti-communist, Berlin Wall, British Empire, California gold rush, colonial rule, cuban missile crisis, Deng Xiaoping, European colonialism, facts on the ground, failed state, Fall of the Berlin Wall, Hans Island, LNG terminal, market fragmentation, megacity, Mercator projection distort size, especially Greenland and Africa, Mikhail Gorbachev, Monroe Doctrine, oil shale / tar sands, Scramble for Africa, South China Sea, trade route, transcontinental railway, Transnistria, UNCLOS, UNCLOS

Making it around the cape was a momentous achievement, but once it became unnecessary to do so, the sea journey from Western Europe to India was reduced by six thousand miles. If you look at a world map and mentally glue Alaska onto California, then turn the United States on its head, it appears as if it would roughly fit into Africa with a few gaps here and there. In fact, Africa is three times larger than the United States. Look again at the standard Mercator map and you see that Greenland appears to be the same size as Africa, and yet Africa is actually fourteen times the size of Greenland! You could fit the United States, Greenland, India, China, Spain, France, Germany, and the UK into Africa and still have room for most of Eastern Europe. We know Africa is a massive landmass, but the maps rarely tell us how massive. The geography of this immense continent can be explained in several ways, but the most basic is to think of Africa in terms of the top third and bottom two-thirds.